The present invention relates to an apparatus for controlling an internal combustion engine for vehicles, and more particularly to an apparatus for controlling an internal combustion engine for a vehicle having an electronically controlled-type transmission system, which is capable of carrying out the automatic engaging operation of a clutch smoothly at a high efficiency.
In vehicles powered by internal combustion engines, for automating the operation of a device for changing gears including a friction-type clutch and a gear-type transmission, there has actually been used, for example, an electronically controlled-type transmission system in which actuators are provided in association with the friction-type clutch and the gear-type transmission, respectively, and the actuators are driven by control signals. The automatic clutch engaging operation in this type of conventional device is carried out as follows. When clutch engagement is required for starting the vehicle or changing gears, for example, the speed of the internal combustion engineis maintained at a required engine speed in an isochronous speed control mode wherein the engine speed is controlled so as to be maintained at a prescribed level, or an all speed control mode in which the governing operation is carried out over the entire speed range from idling engine speed to the maximum engine speed. When the operation for engaging the clutch has terminated, the control mode implemented for controlling the engine speed for the vehicle starting or gear changing operation is discontinued and the control mode is returned to the normal one for controlling the speed of the internal combustion engine (for example, to a limit speed control mode in which only the maximum engine speed and the idling engine speed are controlled and governing operation is not effected in the medium engine speed range). (See, for example, Japanese Patent Application Disclosure No. 68850/84).
However, in the case where the speed control mode of the internal combustion engine is changed-over as described above, there is the drawback of a mechanical shock occurring due to the difference in the fuel injection quantity required for the respective control modes when the isochronous or all speed control modes are changed-over to thenormal mode. In order to avoid the occurrence of such a mechanical shock, the conventional apparatus is constructed so as to use a semi-engaged condition of the clutch when the speed control mode is changed-over, whereby the shock that arises at the time of the change-over of the speed control mode is avoided.
However, when the clutch is used in the semi-engaged condition in order to avoid the occurrence of shock at the time of the change-over of the speed control mode, there is te problem of the clutch plate being subjected to intense friction and the service life of the clutch being shortened.